This invention relates to a meter device for a vehicle which is suitable for use in vehicles such as automobiles.
Referring to FIG. 7, a prior art meter device 01 for a vehicle used in automobiles, which is illuminated from the backside and changes in color of letters and scale marks 02 (hereinafter referred to as "marking 02") between night and daytime. FIG. 8 is a sectional view of a dial plate of the prior art meter device 01. Referring to FIG. 8, a transparent base plate 04, based on such a material as polycarbonate sheet and having the marking 02 and a dial face 03, is printed on it at the locations corresponding to the marking 02 with translucent white layers 05 and on the portions of the dial face 03 other than the marking 02 with an opaque mask 06 of a contrasting color. These translucent white layers 05 and the contrastingly colored mask 06 are covered by a clear layer 07. On the other hand, portions corresponding to the marking 02 on the backside of the base plate 04 are printed with translucent green layers 08, and a translucent white layer 09 is provided on the backside of the base plate 04 corresponding to the translucent green layers 08 and the rest of the dial face 03.
With such a dial plate of the above arrangement, the dial face 03 looks colored and the marking 02 looks white in daytime but, at night, by lighting with a green lamp bulb 010 disposed at the rear side of the vehicle meter device 01, only the marking 02 allows green light to pass, and the dial face 03 looks black and the marking 02 looks green. The translucent white layer 09 provided on the backside of the base plate 04 is to diffuse the light from the lamp bulb 010.
FIG. 9 shows the structure of an indicator 011 used in such a vehicle meter device 01. As shown in FIG. 9, an indicator body 012 is made of a transparent material, which is provided on its lower surface with a colored hot stamp 013. Light from the lamp bulb 010 is collected by a light guide plate 014 to a rotational center 015 and, by a reflecting light source 016, is reflected in the longitudinal direction of the indicator body 012. The reflected light is scattered by the hot stamp 013 provided on the lower surface of the indicator body 012, whereby the indicator body 012 emits light. Since the indicator body 012, as shown in FIG. 10, has a trapezoidal cross section, light diffused by the hot stamp 013 is transmitted mostly from an upper surface 017, formed wider, of the indicator body 012, thereby improving the visibility of the indicator 011.
However, as described above, the prior art meter 01 changes only the color of its marking 02 between day and night, and the marking lights green in the night, and is not attractive in appearance.
Moreover, in the twilight time, when the dial face 03 is light in color, illuminated marking 02 looks blurred and is hard to read because of an insufficient contrast.
Further, with the above described indicator 011, light beams 020 and 021 coming through slanted sides 018 and 019 of the trapezoidally-sectioned indicator 011 illuminate areas 022 and 023 around the indicator of the dial face 03 which, especially when the dial face 03 is of light color, causes halation on the dial surface and makes the indicator 011 hard to be read.